Field of the Invention
The present invention lies in the field of conveying technology and relates to a device and to a method for conveying and transferring flexible, flat objects. The device includes a gripper conveyor with a plurality of grippers that are movable in a conveying direction along a conveying path, moreover a conveying-away device with a conveying rest that is arranged in a transfer region below the conveying path of the gripper conveyor such that objects released by grippers in the transfer region are deposited onto the conveying surface. The device further includes pressing devices that are designed in order, in the transfer region, to the press the objects to be transferred, onto the conveying rest such that the objects are deposited onto the conveying rest in a guided and controlled manner.
Description of Related Art
Increasingly more complex, flexible flat objects are conveyed and/or processed in another manner in printing room technology, in particular with the production of newspapers. The objects, for example, can be individual products, in particular printed products, such as newspapers, magazines, brochures or books.
More complex objects however consist of several products, hereinafter called product units. Such product units, for example, can be collections of products, which are laid onto one another. Moreover, such product units can also consist of one or more products with inserted supplements. Products units of products that are laid onto one another as well as inserted into one another are likewise known.
Moreover, it is known to insert supplements such as flyers, brochures, leaflets, goods samples, etc. into folded products, such as newspapers.
Common to objects of several products of the type described above is the fact that the individual products are grouped loosely together during their conveying. Product units with products laid onto one another as well as inserted into one another must therefore be held together by way of conveying means, such as, e.g., grippers, during their conveying.
Thus, one can also envisage the objects each including several products that are held by the gripper in manner offset to one another and that are also to be transferred with this offset.
The complexity of the objects therefore demands a very precise control of the position of the individual products at each point in time of the processing, in particular also on transfer of the objects between two conveying devices.
The grippers are opened on transfer of objects from a gripper conveyor to a conveying rest, which is arranged in the transfer region below the gripper, wherein the objects are deposited onto the conveying rest lying therebelow by way of gravitational force. Thereby, the objects are situated in freefall for a brief period of time and are therefore in an uncontrolled condition.
It is possible for the individual products to displace or rotate relative to one another when being deposited onto the conveying rest, since the individual products of the object are no longer held together by the grippers on opening the grippers. This can lead to errors with the further processing.
Devices are known, with which design measures have been a taken, which are to permit an as guided as possible deposition of objects from the grippers of a gripper conveyer onto a conveying belt of a conveying-away device.
Thus, the published document EP 2 386 512 A1 describes a device with a gripper conveyor as well as with a belt conveyor of a conveying-away device, which in the transfer region is arranged below the gripper conveyor. The belt conveyor is designed as a vacuum belt conveyor, which in the transfer region sucks the end section of the object that faces the vacuum conveying belt and lies on this already before the transfer, onto the vacuum conveying belt before the grippers are opened. The object is prevented from dislocating on opening the grippers during the unguided deposition of the object onto the conveying belt by way of this.
If the object includes several products that are loosely grouped together, e.g., products that are laid onto one another or inserted into one another, then as was hitherto the case, there exists the danger of the individual products of the object displacing with respect to one another. The lower the adhesive friction between the individual products, the greater is this danger.
This problem can be reduced by way of keeping the distance between the gripper jaw and the conveying rest as low as possible in the transfer region, so that the unguided path of the object from the gripper jaw to the conveying rest is as small as possible. This, however, necessitates the objects in the transfer region being led in an as narrow as possible gap between the gripper and conveying rest. This, in turn, limits the flexibility of the device with respect to the size, the type and the composition of the objects to be processed.
The solution for a transfer of objects from a gripper onto a conveying rest lying therebelow in a controlled and guided manner and which is described in the publication document WO 2010/051650 includes grippers with two gripper jaws, wherein a trailing gripper jaw is lengthened compared to the leading gripper jaw and includes a gripper part which, in the clamping position, extends beyond the leading gripper jaw. The objects in the transfer region are then pressed onto the conveying rest during the transfer from the projecting gripper part of the trailing gripper.
The described device, although permitting a release of the objects onto the conveying rest in a guided and controlled manner, the grippers, however, must be considerably modified for this, which for example entails the retrofitting of existing gripper conveyors at a considerable expense. Moreover, the processing speed of the device is limited, since otherwise the mechanical loading upon the extended gripper limb, which is moved through the transfer region, becomes too great.
In this context, it was otherwise ascertained that a controlled guidance of the objects on transfer onto the conveying rest is particularly necessary at low conveying speeds. This is due to the fact that at high conveying speeds, the inertia forces ensure that the products do no displace or rotate relate to one another during the short but critical transfer phase. The transfer phase accordingly lasts longer and the inertia forces are lower at low conveying speeds.
Low conveying speeds also occur temporarily with devices that are usually operated at high conveying speeds. Thus, the conveying speeds are low when starting the device from standstill or on stopping the device over a certain period of time, which in particular is characterised by an acceleration or braking ramp.
A starting-up of the device, however, is not only necessary on assuming operational production, but also after interruptions due to malfunctioning. A stoppage of the installation accordingly not only entails the finishing of the production, but can also be due to a production disturbance.
Moreover, it can occur that the device must be operated at a lower speed over a certain period of time or over the complete duration of the production for various reasons, for example due to extremely complex objects being processed.